LINE FOLLOWING ROBOT -III

Hello again.. so far we discussed about the sensor panel and the motor drive system of the line follower.. In order to finalize this, we need to program it and finish the structure.. From this article I will explain about the control system and the structure..

Controller

The earlier connected sensor panel and the motor drive system should be connected in order to make the robot work according to the senses received by the sensors. That part is done with the use of Arduino Board. The sensor arrays are connected to the arduino through analog pins and sensor panel gets power to its operation from the arduino (52 port).

Figure 1- The Arduino Board

According to the sensor values received, the arduino is programmed to pass a PWM value to In1, in2, IN3 and In4.This PWM value allows to control the speed of the motors.

PWM (Pulse With Modulation ) :

PWM technology is used to control  the speed of motors. Here the process of varying the width of voltage pulses takes place.

Figure 2- PWM Waveforms

According to the figure above, it is clear that by varying the existing time of high (12V) and low(0V) voltages, the average voltage of each instance can be changed. Therefore the speed can be changed. Here the maximum PWM value is 255 and minimum is 0. By assigning any value in between these to values, the rotation speed of the motors can be controlled.

Structure

The structure is done with Perspex .This has 3 wheels where two main wheels are directly connected to the 2 motors. The 3^rd wheel is at back . At the front , the sensor panel is connected closer to the ground.

Figure 3 - The final structure without circuits

Figure  4 –The Final Line Following Robot

I have not given the arduino coding or the program for the bot.  It is because the code is something to think and do..I hope you will be able to do the correct coding and complete the simple line following robot.. 

Now I think you got a basic understanding about the line follower and Thank you very much for reading..

Special Thanx to Vibhatha, Lakshan, Anuradha and Prabhodi

LINE FOLLOWING ROBOT - II

 
THE MOTOR DRIVE SYSTEM

Hello again. Earlier we discussed about the sensor panel of the line following bot and from this article I'm going to explain about the motor drive system of this bot.

Here the motor drive system is based on the L298 IC.  L298 IC is a high voltage, high current dual  full-bridge driver. Two separate motors can be connected to these two H-Bridges.                                                           

                            

                               Figure 1 - L298 IC                                              Figure 2– H- Bridge

                                                     

Figure 3- Motor Drive Circuit connected to L298 IC

Here there are two separate input couples for the two motors. And along with the inputs, there are two enable pins to operate the two motors.  Two  enable inputs are provided to enable or disable the device independently of the input signals. i.e. even though  In1 and In2 receive logic ‘1’, the motor still does not operate until EnA enable pin receives a logic ‘1’.

                         Table1 – Motor Behavior according to the given inputs

		Motor Behavior
EnA = 1	In1 = 1    In2 = 0 In1 = 0    In2 = 1 In1 = In2	Turn to Right Turn to Left Sudden Stop
EnA = 0	In1 = 1 or 0 In2 = 1 or 0	The motor rotates freely or stay at rest

   

   

 Here In1,In2 and EnA  inputs are to control motor 1. The motor 2 is controlled by In3,In4 and EnB. Two outputs from Pin2 and Pin3 of the IC are taken to connect motor1 and motor 2 is connected to the outputs taken from Pin 13 and Pin 14. When connecting these outputs taken from the IC to the motor, D1, D2, D3 and D4 free willing diodes also should be connected to the motor. For this purpose fast recovery diodes should be selected. Here we have used 1N4148 diodes.

Figure 4 –The Final Motor Driver Circuit

From the female ports included in the circuit as shown, the two motors and inputs can be connected.

So I guess you got some idea about the motor drive system and thank you for reading.